Hi, lupe267.
Welcome to the Apple Support Communities. We’re glad you decided to reach out about adding emojis and stickers to messages on your iPhone. From your description, it sounds like a sticker pack that you enjoyed is no longer showing in the app drawer in Messages.
First, check to see if it’s possible the app just got deleted from the app drawer.
Swipe on the app drawer until you see the “…” icon named “More”. Tap Edit and, if you see the sticker app in the “More Apps” section at the bottom, move it up to “Favorites”.
If you don’t see it here, you may be able to find one that you enjoy in the App Store:
If you’re referring to the emoji options that are missing from your Messages app, see the “Don’t see the emoji keyboard” section here:
Use emoji on your iPhone, iPad, and iPod touch - Apple Support
All our best.